1. Field of the Invention
The present invention relates to a porous body having pressure resistance and to a honeycomb-shaped ceramic separation-membrane structure.
2. Description of Related Art
In recent years, there has been used a ceramic filter in order to selectively collecting only a specific component from a mixture (mixed fluid) of many components. Since a ceramic filter is superior to an organic polymer filter in mechanical strength, durability, corrosion resistance, and the like, it is preferably applied to removal of suspended substances, bacteria, dust, and the like in liquid or gas in the wide fields of water treatment, exhaust gas treatment, medicine, food, etc.
In such a ceramic filter, it is necessary to make the membrane area (area of the separation membrane) large in order to improve water permeability with securing the separation performance, and, for the purpose, it is desirable to have a honeycomb shape. Furthermore, a honeycomb-shaped filter (honeycomb-shaped ceramic separation-membrane structure) has advantages of being hardly broken and cost saving in comparison with a tube-typed filter. In many cases, a honeycomb-shaped ceramic separation-membrane structure has a circular columnar external shape and is provided with a porous base material having a large number of parallel flow passages (cells) formed in the axial direction of the structure inside the structure. Furthermore, a separation membrane (separation layer) having small pore diameter in comparison with the porous base material is formed on the inside wall faces forming the cells.
In the honeycomb-shaped ceramic separation-membrane structure (precise filtration membrane, ultrafiltration membrane, pervaporation membrane, gas separation membrane, and reverse permeation membrane), it is desirable to increase the permeation flow rate by applying high pressure upon operation. In particular, in ultrafiltration, gas separation, and a reverse osmosis membrane, since the permeation coefficient of the separation membrane is small, it is necessary to perform separation and refinement with applying high operating pressure. The Patent Document 1 discloses a base material for zeolite having high corrosion resistance. The Patent Document 2 reports a pressure resistant zeolite separation membrane having a zeolite membrane thickness of 5 to 30 μm. The Patent Document 3 discloses a cross-flow filtration device having an improved permeation flow rate.